Refine WifiTetherSoftApManager and DataSaverBackend to avoid activity leaks

- Declare the service callback as static class and use WeakReference to avoid the callback link being occupied

- Use application context instead of fragment context to avoid context being occupied by external modules

Bug: 237273138
Test: manual test
make RunSettingsRoboTests ROBOTEST_FILTER=TetherSettingsTest
make RunSettingsRoboTests ROBOTEST_FILTER=WifiTetherPreferenceControllerTest

Change-Id: Icca145b8ef08b9949feafbbd4e761f8d50c99181

src/com/android/settings/datausage/DataSaverBackend.java

@@ -27,6 +27,8 @@ import com.android.settings.overlay.FeatureFactory;
 import com.android.settingslib.core.instrumentation.MetricsFeatureProvider;
 import com.android.settingslib.utils.ThreadUtils;
 
+import org.jetbrains.annotations.NotNull;
+
 import java.util.ArrayList;
 
 public class DataSaverBackend {
@@ -43,10 +45,11 @@ public class DataSaverBackend {
     private boolean mDenylistInitialized;
 
     // TODO: Staticize into only one.
-    public DataSaverBackend(Context context) {
+    public DataSaverBackend(@NotNull Context context) {
-        mContext = context;
+        // TODO(b/246537614):Use fragment context to DataSaverBackend class will caused memory leak
-        mMetricsFeatureProvider = FeatureFactory.getFactory(context).getMetricsFeatureProvider();
+        mContext = context.getApplicationContext();
-        mPolicyManager = NetworkPolicyManager.from(context);
+        mMetricsFeatureProvider = FeatureFactory.getFactory(mContext).getMetricsFeatureProvider();
+        mPolicyManager = NetworkPolicyManager.from(mContext);
     }
 
     public void addListener(Listener listener) {

src/com/android/settings/wifi/tether/WifiTetherPreferenceController.java

@@ -56,8 +56,9 @@ public class WifiTetherPreferenceController extends AbstractPreferenceController
     WifiTetherSoftApManager mWifiTetherSoftApManager;
 
     public WifiTetherPreferenceController(Context context, Lifecycle lifecycle) {
+        // TODO(b/246537032):Use fragment context to WifiManager service will caused memory leak
         this(context, lifecycle,
-                context.getSystemService(WifiManager.class),
+                context.getApplicationContext().getSystemService(WifiManager.class),
                 context.getSystemService(TetheringManager.class),
                 true /* initSoftApManager */,
                 WifiEnterpriseRestrictionUtils.isWifiTetheringAllowed(context));

src/com/android/settings/wifi/tether/WifiTetherSoftApManager.java

@@ -5,6 +5,7 @@ import android.net.wifi.WifiManager;
 import android.os.Handler;
 import android.os.HandlerExecutor;
 
+import java.lang.ref.WeakReference;
 import java.util.List;
 
 /**
@@ -15,23 +16,14 @@ public class WifiTetherSoftApManager {
     private WifiManager mWifiManager;
     private WifiTetherSoftApCallback mWifiTetherSoftApCallback;
 
-    private WifiManager.SoftApCallback mSoftApCallback = new WifiManager.SoftApCallback() {
+    private WifiManager.SoftApCallback mSoftApCallback;
-        @Override
-        public void onStateChanged(int state, int failureReason) {
-            mWifiTetherSoftApCallback.onStateChanged(state, failureReason);
-        }
-
-        @Override
-        public void onConnectedClientsChanged(List<WifiClient> clients) {
-            mWifiTetherSoftApCallback.onConnectedClientsChanged(clients);
-        }
-    };
     private Handler mHandler;
 
     WifiTetherSoftApManager(WifiManager wifiManager,
             WifiTetherSoftApCallback wifiTetherSoftApCallback) {
         mWifiManager = wifiManager;
         mWifiTetherSoftApCallback = wifiTetherSoftApCallback;
+        mSoftApCallback = new WifiManagerSoftApCallback(this);
         mHandler = new Handler();
     }
 
@@ -43,6 +35,14 @@ public class WifiTetherSoftApManager {
         mWifiManager.unregisterSoftApCallback(mSoftApCallback);
     }
 
+    void onStateChanged(int state, int failureReason) {
+        mWifiTetherSoftApCallback.onStateChanged(state, failureReason);
+    }
+
+    void onConnectedClientsChanged(List<WifiClient> clients) {
+        mWifiTetherSoftApCallback.onConnectedClientsChanged(clients);
+    }
+
     public interface WifiTetherSoftApCallback {
         void onStateChanged(int state, int failureReason);
 
@@ -53,4 +53,31 @@ public class WifiTetherSoftApManager {
          */
         void onConnectedClientsChanged(List<WifiClient> clients);
     }
+
+    // TODO(b/246537032):Need to declare the service callback as static class and use
+    //  WeakReference to avoid the callback link being occupied by WifiManager
+    private static final class WifiManagerSoftApCallback implements
+            WifiManager.SoftApCallback {
+        WeakReference<WifiTetherSoftApManager> mMyClass;
+
+        WifiManagerSoftApCallback(WifiTetherSoftApManager controller) {
+            mMyClass = new WeakReference<>(controller);
+        }
+
+        @Override
+        public void onStateChanged(int state, int failureReason) {
+            WifiTetherSoftApManager controller = mMyClass.get();
+            if (controller == null) return;
+
+            controller.onStateChanged(state, failureReason);
+        }
+
+        @Override
+        public void onConnectedClientsChanged(List<WifiClient> clients) {
+            WifiTetherSoftApManager controller = mMyClass.get();
+            if (controller == null) return;
+
+            controller.onConnectedClientsChanged(clients);
+        }
+    }
 }